Aviation trainer



Sept. 28, 1948. I L 2,450,239

AVIATION TRAINER Filed July 29, 1942 I 4 Sheets-Sheet 1 FIG. 2 I INVENTOR.

BY WAT 3451M ATTORNEY v KARL A. KAIL Sept. 28, 1948. K. A. KAlL AVIATION TRAINER 4 Sheets-Sheet 3 Filed July 29, 1942 FIG. 7

KARL AKAH.

INVENTOR.

A'.TTORNEY I 4 Sheets-Sheet 4 Filed July 29, 1942 KARL A. KAI L INVENTOR BY w /xfw ATTORNEY Patented Sept. 28, 1948 AVIATION TRAINER Karl A. Kail, Montrose, Pa., assignor to Link Aviation, Inc., a'corporation of New York Application July 29, 1942, Serial No. 452,739

33 Claims.

This invention relates to trainers for aviators, and comprises means for simulating in a grounded aviation trainer the response of an airplane and many of the instruments thereof to certain conditions of flight.

My invention has been found to be particularly useful and will be described in connection with an aviation trainer which constitutes essentially a simulated aircraft fuselage mounted upon a universal joint whereby the trainer can be turned, pitched, and banked in all the usual flying positions of a real plane, Such a trainer is disclosed in U. S. Patent 1,825,462. United States Patent 2,099,857 discloses means whereby the functioning of certain of the instruments in an airplane, such as the altimeter, vertical speed indicator and air speed indicator may be simulated in such a trainer.

One of the principal objects of this invention is to provide in such a trainer means whereby the functioning of certain of the instruments in an aircraft other than those mentioned above may be simulated.

One of my more specific objects is to provide means whereby the functioning of the tachometer and manifold pressure gauge in a plane may be simulated in a grounded aviation trainer, and also means whereby the functioning of these instruments in a dual motored aircraft may be simulated in such a trainer. I propose to provide means whereby a change in the attitude of such a trainer will change the indications of the manifold pressure gauge and the tachometer in the trainer in the same manner that a like change in the attitude of a plane in flight affects the manifold pressure gauge and tachometer therein.

It is also a specific object of this invention to provide means whereby a change in the throttle setting in the trainer will change the indicated assumed manifold pressure and motor speed in the same manner that a like change in the throttle settingof a plane in flight will change the reading of the manifold pressure gauge and tachometer therein.

Still a further object of this invention is toprovide means in such a trainer whereby the assumed motor manifold. pressure will be varied by a change in the assumed altitude of the trainer.

My invention will be illustrated when it is adapted to simulate in a grounded aviation trainer the functioning of the manifold pressure gauge or gauges and tachometer or tachometers in a plane equipped with a fixed pitch propeller, but it will be understood by those skilled in the art that many features of my invention are read- 2 ily adaptable to simulating the functioning of the manifold pressure gauge or gauges and tachometer or tachometers in a plane equipped with other kinds of propellers-for example variable pitch, or as they are often called, constant speed propellers.

In a companion abandoned application Serial No. 448,906 filed June 29, 1942, wherein the present inventor is named as a joint inventor means are disclosed whereby in an assumed dual motor trainer the air speed indicator, vertical speed. indicator and altimeter may be made to respond to a change in the setting of either of the throttles in the trainer in the same manner that the same instruments in a dual motored plane in actual flight respond to a corresponding change in the setting of one or both of the throttles in the plane. It is a further object of the present invention to incorporate in an assumed dual motor trainer having certain instruments that respond to a change in the setting of either of the throttles means whereby each of the manifold pressure gauges and tachometers responds to a change in the setting of but one of the throttles in said trainer, i. e., the throttle which is assumed to be associated with the same engine that the responding manifold pressure gauge and tachometer is assumed to be associated.

Also disclosed in said companion application are means whereby an assumed dual motor trainer may be made to rotate about its vertical axis when the throttle settings therein are unequal, thereby simulating the rudder loading which occurs in a dual motor plane when the engines are not synchronized. It is another object of the present invention to provide means whereby even though an unequal setting of the throttles be present the turning of the trainer caused by such .unequal throttle settings will be decreased as the trainer is banked, thereby simulating the diminishing of rudder loading as a real plane is banked.

Also, it is an object of my invention to provide manually operable means under the control of the student in the trainer for compensating for such a rudder loading in orderthat the rotation of the trainer caused by unequal throttle settings may be prevented.

Other objects and advantages will become apparent as the description proceeds, reference now being made to the accompanying drawings forming a part of this application and wherein like reference numerals indicate like parts.

In the drawings,

Fig. 1 is a side view of an aviation trainer in Fig. 3A is a view-of a compensating. link that may form a partgof my invention,

Fig. 4 is a View of one of the bellows, the sectional part taken on the line IVIV in Fig. 3.

Figs. 5, 6, and 7 are detailed views of the parts of one of the valves of this invention.

Fig. 8 shows the parts drawn, in .thethre re ceding figures in assembled relation.--

Fig. 9 is a diagrammatic illustration of a portion of the control system of my inventionz" Fig. 10 is a detailed view of the air speed regulator bellows.

Referring to Fig. 1, it will be. seen that. such av trainercomprises a fuselage It! 'mountedupon a universal joint designated-generally. as l2 which? in turn rests upon a central supporting member [5. Two pairs of bellows I6 and I8 are provided,

only one of the bellows l8 being visible, however,

in Fig.. 1. Each pair of bellows is connected by separate connecting lines to the turbineifiiwhich. is the source of vacuumandin each oftheicon necting lin'esis a valve operated by the control stick in the trainer; I These connecting/lines,

valves,-and stick are liOtfShOWD. The bellows. 16

are fore and aft of the trainer andfiare referred to as the elevator bellows whilethe valve between 'these bellows and the source of vacuum 20 'is The other'pair' t referred to as the, elevator valve.

of bellows .18 and the correspondingvalve are;

referred so as the aileron bellowsiandvalve respectively; Upon the pushing forward 'of the stick'in 'thetrainer by the student, the elevator valve is'moved 'tdsuch a position thatwacuumz is admitted to'the' forward bellows I 6; while at the same time atmosphere is. admitted. to the 'rear-' ward bellows'lfigcausing the forward bellows to collapse. and the rearward .bellowstto expand;

thus forcing the trainer to'a diving .attitude:. By"

pulling the stick rearward,'the-bellows respond in an opposite manner. and the'trainerfassumes a climbing attitude. movement of thestick' sideways, the trainer may be .made to bank in the: desired direction; It will thereforebe-realized that such a trainer may be made to pitch and bank in any desired direction;

There is also connected to the trainer fuselage" by means of extendingarm23'a turning motor 22;

In 'a similar manner, by"

the'output'shaft of which has a pulley: (notr' shown) fixedly mounted thereupon; The main.

support 15 of the fuselage .10 is mounted 'on"an-' other support19 which in; turn "is 'rotata'b'ly mounted" in a receiving "member-"(not-shown)' which 'at all times remainsstationary; and an" annular groove (not shown) is integral with this";

fixed member. An endless belt 2| around this annular'groove aswell as around the fixed pulley on the end of the output shaft' 'of said turningmotor 22; The turning -motor;221is also is placed connected to, the sourceof vacuum 20,-there being; in the connecting means a rudder valve which is operated bythe rudder pedals in the trainer; Wh'enthe studentin the trainer applies either foot to. one of the rudder pedalsytherudder valve linkv is moved. and the. rudder valve isgaffectedj so that reduced air pressure is admitted to.the,.,

appropriate side of the turning motorfw'hichis in -reality a double-acting-air motor).- and, the out.-

put shaft of the turning motor is rotated in the correct direction, thereby rotating the pulley fixed thereto. Since the endless belt 21 wraps around the annular groove which is integral with the stationary member that receives supporting member [9, the rotation of the fixed pulley of the turning motor will cause the turning motor 22 to turn itself, extending arm 23, trainer fuselage Ill, universaljoint l2,'and support 55 about the vertical axis of support i9, which axis is also considered to be the vertical axis of the trainer fuselage.

All the above functioning forms no part of the present invention except as combined with the novel .features of the instant invention, and, thereforeya more detailed description is omitted, but for a full disclosure reference is made to the above-mentioned U. S. Patents 1,825,462 and 2,099,857.; However, in the light of the foregoing discussion, the objects of the instant invention and the following means of attaining them will be'more readily understood;

Reference is made'to Fig. 3 which discloses means-used in the preferred embodiment of my invention for simulating in a grounded aviation trainer the indications of the manifold pressure gauge of a plane in actual flight. Those familiar with the rules ofiaviation realize that whenever thethrottle associated with a given motor in a real plane is moved a changein the gauge which indicates the 'manifold pressure of that motor results:

In that figure, it will be seen that a simulated throttle lever 38 is. pivotally mountedat the point .32and has pivotally connected to its lower end a link 34,"the. other end of which is .pivotally attached to the upper, end of bell crank 36. Attached to the other end of bell crank 38 is link 38, the lower endof which is pivotally attached to .arm Arm All has a companion arm :32, and

both of these arms are rigidly affixed to shaft 44. Right angle extension is integral with arm 40 while a corresponding part as is integral with arm 42. Shaft 44 is free to turn in arm which in turn is rigidly affixed to shaft M4. Because of this arrangement it will be realized that whenever link 381s moved up or down through a movement of bell crank '36,; link 34 and throttle 3ll,both of the arms "40- and-42 will be moved in the same .direction and to the same extent.

Pivotally connected to the end of arm 62 farther 'from'shaft 44 is the upper end of link 52 and rigidly affixed to the lower end of link 52 is the upper. end of bellows 54 which is preferably made of metal and ofthe expansible, contractible type: Rigidly affixed to the lower end of this bellows is link 56,1 the lower end .of which is free to slide'up and down in the extension 58 of bellows designated generally as 60. A spring 62 is inter- ,posedbetween the lower end. of the bellows 54 and the extension .58;

The upperportion of the bellows which is the assumed leftmotor manifold pressure bellows is rigidly affixed to any suitable part of the trainer ,fuselage while the lower portion is movably pivoted at the left end (as seen in Fig. 3) of the upper.

fixedpart of'thisbellows which is made air-proof by "means of suitable, covering material.

Bellows'60 shown'in .detail in Fig. 4 has two ports. and 66;port 64 being connected by means of hose .68 to. regulator bellows H! which in turn isconnected to manifold lZ'by means of hose l4.

Regulatorbellows it maybe of any suitable'type. providingit maintains across itstwo side a-de- ,sirednonstanm differential pressure. Port 66 is connected to manifold pressure gauge I6 by means of hose I8. Bleed hole 82 is provided in hose 78 which connect port 66 with the manifold pressure gauge I6. This gauge, as inferred above, indicates the assumed left motormanifold pressure. In Fig. 4 it will be seen that within bellows 60 is a needle valve designated generally by 80, which valve is positioned opposite port 64. Thus, when this needle valve is opened, reduced air pressure from manifold I2 will be applied through connection I4, regulator bellows l0, hose 68 and port 64 to manifold pressure bellows 6G. Manifold pressure gauge 16 will indicate the change in pressure within that bellows.

As stated above, the upper part 85 of bellows 60 is stationary while the lower part 81 is pivotally connected to the upper part at the left end 89 as seen in Fig. l. Rigidly connected to the opposite end of part 81 is the extension 58 previously mentioned. Vertical rod 56 is free to slide in the central opening in this extension. Spring 63 prevents the bottom 81 of bellows 63 from falling down too far when there is not sufficient vacuum within that bellows;

As the air pressure within bellows 60 becomes gradually decreased through the action of manifold I2, this bellows gradually collapses until the pressure therewithin and the action of spring 62, which two forces tend to expand bellows 6!! and open needle valve 80 exactly equal the atmospheric pressure on the outside of bellows 56 which latter force tends to collapse said bellows and thus close needle valve 80. When these opposing forces are balanced, vacuum source I2 will exhaust from bellows 60 the same amount of air that enters that bellows through bleed hole 82 in hose I8.

Because of the above equation of forces it will be realized that by varying the compression upon spring '2 the amount of vacuum necessary within bellows 60 to balance the atmospheric pressure on the outside of this bellows may be varied. This varying vacuum will in turn vary the reading of manifold pressure gauge I6.

Hence, by moving the lower end of metal bellows 54, the compression upon spring 62 will be changed as will the vacuum within bellows 653. The greater the compression upon spring 62 the greater will become the vacuum within bellows 6B and the greater will be the indicated manifold pressure.

Those familiar with the rules of aviation will realize that an opening of the throttle associated with an engine in a plane will cause the manifold pressure gauge assoc'iated with that engine to indicate an increased manifold pressure. Referring to Fig. 3, an opening of throttle til, i. e., a movement to the left in that figure, will cause link 34 to move to the right and the lower end of bell crank 36 will be moved downward a will link 38. The end of arm 68 to which link 38 is connected will also be moved downward and through the action of shaft M the corresponding end of arm 42 will move in the same direction.

Link 52 and bellows will also move downward as will link 56. Because the lower end of bellows 54 is so moved, the compression upon spring 62 will become increased through the action of the spring upon extension 58, this spring will force the bottom portion 86 of bellows 6i! to move downward and needle valve 8i! will be opened. Vacuum from manifold I2 will therefore be ap plied to bellows 50. The vacuum within bellows 60 will become gradually increased until the pressure within that bellows and the compression upon spring 62 exactly equal the atmospheric pressure upon the outside of that bellows. Consequently, a gradual increase in the indicated manifold pressure will result until this point is reached.

On the other hand, if throttle 30 be closed,

that is, moved to the right in Fig. 2, link 38 will be moved upward as will the right, ends of arms 40 and 42, link 52 and bellows '54. The compression upon spring 62 will therefore become decreased and the needle valve 89 will tend to close. Less air will therefore be exhausted from the bellows than enters through bleed hole 82, and the pressure therein will increase until the compression upon spring 62 plus the pressure within bellows 6i! exactly equals the atmospheric pressure on the outside of this bellows. When this point is reached as much air will be exhausted by manifold l2 as enters the bellows through bleed hole 82. A gradual decrease in the manifold pressure a indicated by gauge 16 will occur until the point of equilibrium is reached.

It will be seen from Fig. 3 that throttle 84, link 86, bell crank 88, link 90, member 9!, arms 92 and 94, shaft 96, link 98, bellow IE9, vertical link I02, spring IM, bellows designated generally as 5536, spring I88, ports III! and H2, connection IId, bleed H5, and manifold pressure gauge H6 comprise a second independent manifold pressure system which is identical in all respects with the one which has been described in detail above. A further description of this system is unnecessary, it being deemed sufficient to state that this latter system which governs the reading of manifold pressure gauge H6 is assumed to be asso-- ciated with the assumed right motor in the trainer. It will be realized that an opening of throttle 84, i. e., a movement to the left in Fig. 3 will cause an increased compression upon spring Iild, a greater vacuum within bellows I86 will result, and manifold pressure gauge IE5 will indi cate an increased assumed right motor manifold pressure in the same manner that a similar movement of throttle 30 afiects the reading of manifold pressure gauge IE. Also, a closing of throttle 84, that is, a movement to the right in Fig. 3, will result in a decreased indication as given by manifold pressure gauge I I6.

The foregoing arrangement, therefore, provides means in a grounded aviation trainer whereby the simulated motor manifold pressures in the case of an assumed single or dual motor trainer may be made to vary with a change in the setting of a throttle or throttles in the same manner that the manifold pressure gauge or gauges in a ,plane in actual flight vary with a corresponding change in throttle settings.

The second factor which affects the manifold pressure of the motors of a plane in flight is the attitude of the ship, that is, Whether it be climbing or diving. The following -means are incorporated in this invention in order that the reading of manifold pressure gauges l6 and He will respond to a change in the attitude of the trainer.

Referring to Figs. 2 and 3, horizontal shaft I28 is mounted for rotation in brackets I3 I, only one of which is shown, and the end of shaft I28 nearer central support I5 has rigidly affixed thereto a lever I39, the upper end of which has integrally connected to it a horizontal extension it? which in turn has an integral depending member I34. Suitably mounted in the lower part of depending member !34 is a roller I36. R igidly afiixed to the central support I5 of the trainer by means of bolts Z5 :is an upwardly extending member I38. A

7. spring Milwhich has one end connected to any fixed portion I43 of the trainer fuselage maintains roller 36 at all times in contact with extension I58. Shaftl28 and horizontal extension I32 extend laterally of the trainer fuselage. As shown in Fig. 1, the bottom '31 of thetrainer fuselage In is suspended below universal joint I2 by means of brackets I! but the trainer fuselage and the complete mechanism'shown in Fig. 3 except central support I5 also rests upon the top of the universal joint. Because of the fact that the mechanism shown in Fig. 3 is positioned below universal joint I2 and at the same timeit moves with the floor of the fuselage 31 which rests upon the top of this universal joint by means of members I'I; referring to Fig. 3, it will be understood that when the trainer fuselage II] (pitches in simulation of climbing, shaft I28 moves ahead of its level flight position but roller I36 and the lower part of depending arm I34 cannot so move because of stationary extension I 38. Shaft I28 will therefore turn in brackets I3I and the lower end of lever I39 will Ill'lO'VE toward the rear of the trainer, pushing before it link MI to which it is pivotally connected and the upper end, of arm M2 which in turn is pivotally connected to the other end of link Ml. Inasmuch as this arm is rigidly affixed to shaft M4 which runs transversely of the trainer fuselage, this shaft will be made to rotate in a clockwise direction as viewed from the end upon which arm I42 is mounted. Arm 50, as stated previously, is rigidly mounted upon shaft i 34 and it will therefore move in the direction. Shaft 44 and the ends of arms 4i! and 42 which are rigidly affixed thereto will therefore be moved downward. In this instance these two arms will pivot about an axis running transversely of the trainer fuselage and through the point where the link 38 is attached to arm 48. Amns 9J2 and-94 which correspond to arms 43 and 42 because of the action of arm 9| will respond in the same manner. The end of arms 62 and 92 farther from shaft I44 will therefore goup and the compression upon the springs 52 and IE4 will become lessened as will the vacuum within bellows all and I36 and a decrease in the indicated manifold pressures as shown by gauges l6 and I IE will result.

If the trainer were pitched in simulation of a dive, shaft I28 will be moved to the rear of its level flight position and spring I40 will maintain roller 53% against upwardly extending member $38. Shaft l28 will be made to turn in brackets :35 in a direction to cause the lower end of lever 5 as to move toward the head of the trainer. Link I4! will move likewise and the upper end of arm M2 will 'move in a counterclockwise direction as viewed from'the left side of the trainer. Shaft M4 will move in the same direction and theend of arm 5! in which horizontal shaft 44 is pivotally mounted will be moved upward. Arm 9! which corresponds to arm 55 will react in the same manner and the ends of arms 49 and 42 which are connectedto shaft 44 and the ends of arms 92 and l' which are connected to shaft 96 will also be moved upward. Anm 42 will pivot about an axis running transversely of the trainer and through the point where link 38 is attached to arm 40 and therefore the end of arm 42 to which link 52 is connected will be 'moved downward. An increased compression upon spring 52 will result as will an increased indicated manifold pressure. Likewise, arms 92 and $34 will pivot about an axis running transversely of the trainer and through the point where link 901s attachedto arm-92.

8 The-end of arm 92 to which link 98 is attached will bemoved downward and an increased compression upon spring I04 will result, thereby causing an increased vacuum within bellows I06 and an increased manifold pressure as indicated by gauge II6.

By the foregoing means, therefore, the'indicated assumed manifold pressure of each of the motors assumed to be in the trainer will respond to a change in the trainer attitude in the same manner that the manifold pressure of the motor or motors of a plane in actual flight will respond to a change in the attitude of the ship. The manifold pressure of a plane in actual flight depends to a certain extent upon the altitude at which the ship is fiyingthe higher the altitude, other factors remaining constant, the lower the manifold pressure. The following means may form a part of my invention to simulate the effect of altitude upon manifold pressure.

Referring to Fig. 9 an equalizer tank I22 is positioned inside the fuselage It. Connected to the equalizer tank I22 by means of the air connections I220; are the simulated altimeter I24 and vertical speed indicator I26 which function as described in U. S. Patent 2,099,857 to indicate to the student in the trainer la the assumed altitude and vertical speed of the trainer.

In Fig. 9 it will be seen that the equalizer tank I22 is connected by means of air line 406 to the climb valve 302 and by means of air connection de l to the dive valve 4%. The port 4680f climb valve 402 is connected by means of air line M0 to manifold M2, while the port QM of dive valve its communicates with the atmosphere. Manifold M2 is connected by air line 4113 to a suitable source of reduced air pressure. The detailed construction of the climb and dive valves in and of themselves form no part of this invention and for detailed description thereof reference is made to the above mentioned U. S. Patent 2,099,857. For the purposes of this invention it is sufficient to know that each of the valves 402 and 406 is a needle valve, in the case of the climb valve 492 the needle and seat being between the port 4B8 leading to the manifold M2 and the air line 4% leading to the equalizer tank i 22. In the case of the dive valve the needle and seat are between the port el leading to the atmosphere and the air line 494 connected to the equalizer tank. Connected to the needles in each of the valves is a threaded stem the outer ends of which are designated by the numbers did and M8, the former being associated with the climb valve and the latter with the dive valve.

Fixedly connected to the outer end of stem M6 is an operating arm 42d and a corresponding member 422 is likewise connected to the stem M8. Each of the operating arms 42%! and ,22 is pivotally connected to one of the pair of blocks 424 or 26 which are slidably mounted upon reciprocating link 4728. A pair of stops 53B and 432 are fixed to the front of the mounting bracket 434 upon which the climb and dive valves are mounted. When arm ezc is in contact with its stop 439 climb valve is closed and when arm 422 is in contact with its stop 432 the dive valve is closed.

Fixedly attached to the central portion of reciprocating link 4123 between blocks 22d and 26 is engaging member 435, so when reciprocating link 428 moves toward the head of the fuselage Ii), engaging member 336 moves in the same directionpushing block 426 which in' turn carries aea ese arm 422, thereby opening dive valve 488 to permit communication between port 4I4 leading to the atmosphere and equalizer tank I22. At the same time compression spring 438 which encircles the fore end of link 428 and is held thereon by block 428 and stop 448 will remain in its normal state of compression, but spring 442 which encircles the rear end of link 428 and is held thereon by block 424 and stop 444 will be contracted because block 424 and arm 428 are held stationary by stop 438. Therefore, such a movement will not open the climb valve 482. However, a movement of link 428 to the rear of the fuselage I8 will open climbv valve 482, thus admitting reduced air pressure from manifold M2 to the equalizer tank I22, but this movement will not affect the positions of block 428 and arm 422 which are held by stop 432, so the dive valve 488 will remain closed.

Referring to Figs. 3 and 9, it will be seen that there is pivotally connected to the rear arm of bell'crank 88 the vertical link I94 and there is similarly connected to the rear end of bell crank 88 the vertical link I98. The lower ends of each of the links I94 and I98 are pivotally connected to opposite ends of the operating arm I96 which is fixedly attached by means of screws 288 to the outer leaf 246 of the three-leaf valve assembly designated generally 282. This three-leaf valve is attached to the manifold 284 in a manner that will be later described in detail, so that the assembly 282 and manifold 284 may slide with respect to the track 288 which is fixedly mounted to a suitable part of the interior of the fuselage I8. Pivotally attached to the center of cross arm I98 is the upper end of vertical link 288, the lower end of which is pivotally attached to the unpivoted end of arm 458. The other end of arm 458 is rigidly affixed to transverse horizontal shaft 458 which is rotatably mounted upon the bottom 31 of the fuselage I8. of shaft 458 is affixed arm 488 to the upper end of which-is pivotally connected the rear end of link 482. The forward end of link 462 is pivotally connected to the central portion of the pitch action walking beam 484 at the point 483, as shown. This beam is pivotally attached to the horizontal stub shaft 468 at the point 468. To the lower end of the pitch action walking beam 484 is attached the fore end of link 418 which extends rearwardly and is attached to the rearward end of the reciprocating link 428, to which reference has been previously made. Link 418 comprises the well-known conventional centering device designated generally by 412.

Still referring to Figs. 3 and 9 it will be noted that a movement of lever 38 in either direction will move link I94 up or down depending upon the direction of movement of the lever 38. The same is true of the lever 84 and the vertical link I98. When link I94 is moved, link I98 remaining stationary, the arm I96 pivots about the point at which it is attached to link I98. The left end of arm I96 moves up or down, the outer leaf 248 of the three-leaf valve assembly 282 rotating about its center as will later be more fully disclosed, and the whole valve assembly 282 and manifold 284 sliding in track286. This sliding movement will cause a movement of the link 288. On the other hand, when throttle lever 84 is moved, lever 38 remainingstationary, the vertical link I98 moves up or down and the arm I98 is pivoted about the point at which it is attached to link I94. The same sliding movement occurs, resulting in a movement of vertical link 288. The conclusion may be drawn that the- On the left end 10 link 288 is differentially responsive to the movements of the levers 38 and 84. A pushing forward of either of the levers 38 or 84 results in a downward movement of link 288 while the opposite movement of either of these levers results in an upward movement of this link.

A downward movement of link 288, referring to Fig. 9, results in a movement to the rear of links 482 and 418, beam 484 pivoting about the point 488. The movement to the rear of link 418 results in a similar movement of reciprocating link 428, the climb valve 482 is opened an amount dependent upon the movement of link 288.and the equalizer tank I22 is connected to the manifold M2. The pressure within tank I22 is reduced and the altimeter I24 indicates the assumed increase in altitude of the trainer and vertical speed indicator I28 indicates the assumed rate of climb of the trainer. On the other hand, an upward movement of link 288- results in an opening of the dive valve 486, and the tank I22 is connected to the atmosphere through port 4I4, so the pressure in the tank builds up at a rate dependent upon the extent to which the dive valve is opened. The altimeter shows the lower assumed altitude and the vertical speed indicator reflects the assumed rate of descent. It will be appreciated that the rate of change in pressure within tank I22 depends upon the differential movements of the levers 88 and 84, just as the altitude of a dual motor plane depends upon the differential movements of the throttle levers therein. Consequently the instruments I24 and I28 respond to the settings of levers 38 and B4 in the same manner that their real counterparts respond to the setting of the throttle (levers in a real plane.

The second basi c factor which affects the altitude of a plane in actual flight is the attitude of the plane, i. e. whether it is climbing, diving or flying straight and level.

It has been previously explained that when the fuselage I8 pitches in simulation of the climbing of a plane in actual flight the lower end of lever I38 moves toward the rear. Therefore in Fig. 3 the shaft I28 which is affixed to arm I38 will move counterclockwise as seen from the left. Referring to Fig. 9 such a movement of the shaft I28 will result in a counterclockwise rotation of the arm 488 which is affixed upon the left end of shaft I28. The stub shaft 488 therefore moves toward the head of the trainer carrying therewith the upper end of walking beam 484 which in this instance pivots about the point 483. The lower end of arm 484 moves to the rear as do the links 418 and 428 and the climb valve 482 is opened thus resulting in a decrease in the pressure within the equalizer tank I22. Altimeter I24 reflects the increase in assumed altitude of the trainer while the vertical speed indicator I28 indicates the assumed rate of ascent. 7

It will be appreciated that when the fuselage I8 is pitched in simulation of the diving of a plane in actual flight, the shaft I28 is rotated in the opposite direction resulting in a movement of the link 428 toward the head of the fuselage ID. The dive valve 486 is therefore opened connecting the atmosphere port-M4 with the equalizer tank I22 and an increase in pressure in the equalizer tank results. The altimeter I24 reflects the decrease in the assumed altitude of the trainer and the vertical speed indicator I28 shows the simulated rate of descent.

.In view of this explanation :it will be appreciated that the pressure within the'equalizer tank" I22 varies in accordance with the'assumed alti-' tude of the trainer-the higher the pressure within the tank I22 thelower the assumed altitude. The pressure within the tank I22 may therefore be used as a measure of the assumed altitude of the'trainer and this pressure'depends upon the successive combined positions of the levers 30 and 04 combined with pitching attitude of the fuselage I together with the length of time that these successive settings and attitudes have been maintained. Thus the same factors affect the pressure within the equalizer tank I22 as affect the altitude of a real plane in actual flight.

Referring to Fig. 3, the altitude compensator bellows 54 and I00 are connected by air lines H8 and I to the tank I22. Inasmuch as the pressure within tank I22 always varies in accordance with the assumed altitude of the trainer, so will the pressure within altitude compensator bellows 54 and I00. As the pressure within equalizer tank I22 and bellows 54 and I 00 changes these two bellows will expand or contract, and as they do this the compression upon the respective springs 62 and I04 is also changed. An expansion of bellows 54 and I00 will cause an increased compression upon the springs 62 and I04 as was explained above, the vacuum within the associated bellows I50 and I06 will become greater and an increased assumed manifold pressure indication will be given by the appropriate manifold pressure gauges I6 and I I5. On the other hand, a decrease in the pressure within equalizer tank I22 will cause a contraction of the altitude compensator bellows 54 and I00, a decreased compression upon springs 62 and I04 will result, as

, Ia, change in the altitude of the plane.

It will be realized, therefore, that my invention comprises means for varying the assumed motor manifold pressures of a grounded aviation trainer according to the assumed altitude of the trainer.

As far as indicating the assumed manifold pressure of the motor or motors in a grounded aviation trainer is concerned, it may be concluded that my invention provides means whereby the indicated manifold pressure will depend upon the same factors as does the manifold pressure of the motors of a plane in actual flight, these factors being three in number: first, the setting of the throttle or throttles, second, the assumed altitude of the trainer, and finally, the attitude of the trainer.

As stated near the beginning of this description, it is a principal object of this invention to provide means whereby the functioning of the tachometer (which instrument indicates the number of revolutions per minute of the motor with which it is associated) in a real plane in flight may be simulated in a grounded aviation trainer. Referring to Fig. 3, it will be seen that two bellows designated generally as I50 and I52 are provided, the former being the assumed left motor tachometer bellows and the latter being the assumed right motor tachometer bellows." Each of these two bellowsis identical in every respect with the bel1ows60'and105which; it will be recalled, are the assumed left and" right motor manifold pressure bellows 'respec-" tively. Tachometer bellows I50has a port I54 which is connected to vacuum supply line I 55 and regulator bellows I58 is interposed between this bellows and the manifold I2. Regulator bellows I 58 is identical in construction with regulator bellowslll and therefore it may be of any'suitable type provided it maintains at all times across its two sides a constant differentialpressure; Ta' chometer bellows I52 has a port I60 which is also connected to the same vacuum supply line I55 to which tachometer bellows I50 "is also connected. Tachometer bellows' I50 has a second port I62 with which tachometer I64 is in communication by means of connection I66. A bleed hole i68 is present in this connection. Tachometer bellows I52 also has a second port III! with which tachometer H2 is in communication by means of connection I'M. A bleed hole I16 is present in connection H4.

The tachometers I64 and I'Ilwhich'indicate the assumed left and right motor speeds respectively may be of any suitable type provided their indications are responsive to the air pressure within the tachometer bellows to which each is connected, the lower the pressure within these bellows the higher the indicated speed given by the tachometer connected to that bellows.

As before explained in great detail, the pressure within the manifold pressure bellows 60, which bellows is shown in detailin Fig. 4, is dependent upon the compression upon the spring 62 which is associated with that bellows. Inasmuch as the tachometer bellows I50 and I52 are identical in all respects with the" manifold pressure bellows 60, it will be realized that the pressure within each of these tachometer'bellows depends on the compression upon the springs I18 and I which are associated with the ta chometer bellows I50 and I52 respectively. A stop I 82 is mounted upon the'vertical link I84,

the upper end of which is pivotally attached to the arm 40 to which reference has beenpreviously made. The lower end of link I84 slides in the central opening in the extension I86 of bellows I50. In view of the detailed explanation of the functioning of spring 62 which'is as-' socia'ted with the assumed left motorrnanifold pressure bellows 60 it will be readily understood that a movement up or down of the end of arm 40 to which link I84 is connected willdecrea'se or increase respectively the compression upon spring I78 and will therefore cause an increase ordecrease respectively in the pressure within bellows I50. A decrease or increase in the indicated motor "speed as given by tachometer I64 will result.

of the climbing of the plane in actual flight causes theends of arms 40 and 42 to which links I84 and 52*are respectively conne'cte'd'to move upwardly; A decrease in the compression upon spring I18 will therefore result and a like change will occur in the indicated assumed motor speed given by tachometer I64. On the other hand, a pitching of the trainer fuselage in simulation of the diving of a plane in actual flight will cause the end of arm 49 to which link I84 is connected to move downwardly, an increased compression upon spring I18 will result and tachometer I64 will reflect an increased assumed left motor speed.

Referring to the assumed right motor speed indicating system, link I88, stop I90 and spring I80 function exactly as do their counterparts in the left motor speed indicating systems. Therefore, it is deemed unnecessary to show in detail that with an opening of throttle 8A or with a pitching of the trainer fuselage If! in simulation of the diving of a plane in actual flight an increased indication will be given by tachometer I12 and that with a closing of throttle 84 or with a pitching of trainer fuselage ii! in simulation of the climbing of a plane in actual flight this same instrument will give a decreased indication.

The foregoing discloses therefore means whereby the functioning of the tachometer or tachometers in a real airplane may be simulated in a grounded aviation trainer.

It will be appreciated by those familiar with the flying of actual aircraft that the air speed of the craft depends primarily upon two basic factors-the setting of the throttle lever or levers and the climbing and diving attitude of the plane. An opening of the throttle lever or levers and a diving of the plane causes an increase in air speed while a closing of the throttle lever or levers and a climbing of the plane results in a decrease in air speed. It has been explained that the vertical link 268 and Walking beam 284 shown in Fig. 9 are always positioned according to the combined positions of the simulated throttle levers 30 and 84. The position of this walking beam may therefore be used as a measure of the assumed air speed of the trainer insofar as assumed air speed is dependent upon the setting of the simulated throttle levers. Also, when the fuselage I is placed in a diving position the upper end of walking beam 45% is moved toward the rear of the fuselage, in this instance the walking beam pivoting about the point 453, and

a climbing of the fuselage IB results in an opposite movement of the beam 464. Consequently, the position of the walking beam may be taken as a measure of the assumed air speed of the trainer because it is positioned in accordance with the combined positions of the throttle levers and fuselage attitude.

In Fig. 9 it will be seen that there is provided the link 560 which is pivotally connected to the walking beam 465 between the points 463 and 668. The fore end of link 5130 is pivotally connected to the upper end of the air speed reversing arm 532 which pivots about the point 594. To the lower end of arm 562 is pivotally connected the rearwardly extending link 595 to the rear end of which is connected the spring 568. The rear end of spring SE38 is connected to the link 51%) which forms a part of the air speed bellows assembly designated generally 5l2. Reference is made to Fig. 10 which is a detailed disclosure of this assembly. In Fig. 10 the numeral 5% refers to the air proof bellows preferably made of light metal construction. This bellows may be mounted in any suitable manner upon a frame 14 member 5|6 which in turn is mounted on the floor 31 of the fuselage l8. Within bellows 514 is a needle valve designated generally by 558 and comprising a seat 520 and a needle 5222. Seat 52B is rigidly affixed to frame member 516 while needle 522 is attached to link Eli) through suitable connecting means 524. The interior of bellows 5M is connected through the needle valve and line 526 to the manifold M2, as seen in Fig. 9. Also the interior of the bellows is connected by air line 521 to the simulated air speed instrument 528 in fuselage Ill.

When the'lower part of arm 562 is moved toward the head of the fuselage Ill, link 506, spring 598, link 5H1, connecting means 524 and the forward end of bellows 5! will be pulled in the same direction. Bellows 5M will therefore be expanded and at the same time needle 522 will be pulled from its seat 520 and reduced air pressure from the manifold M2 will be applied through connection 526 to the bellows 5M, and as is well known in the prior art, simulated air speed indicator 528 will indicate a higher assumed air speed. An opposite movement of lever 502 results in a lower indicated assumed 'air speed.

It will be appreciated, therefore, that a diving of the fuselage H] will result in an increased indicated air speed while a climbing of the fuselage will result in a decreased indicated air speed, because lever 502 is responsive to the movements of walking beam 464. Further, inasmuch as the lever 592 is responsive to the combined positions of the simulated throttle levers 3i) and 84, the

- indicated assumed air speed is responsive to the combined positions of these two simulated thrott le levers just as the air speed in a dual engine plane is responsive to the combined positions of the throttle levers in the plane. I

Previously in this description it was stated that in said companion application Serial No.

448,906, there was disclosed means whereby an assumed dual motor trainer may be made to rotate about its vertical axis when the throttle settings therein are unequal, thereby simulating the rudder loading which occurs in a dual motor plane when the engines are not synchronized. It was stated to be a further object of this invention to provide means whereby even though an unequal setting of the throttles be present, the turning of the trainer caused by such unequal throttle setting will be decreased as the trainer is banked, thereby simulating the diminishing of rudder loading as a real plane is banked.

Reference is now made to Figs. 5, 6, 7 and 8 which show in detail the construction of the 3-leaf valve 252. Fig. 5 shows in detail the construction of leaf 2H1 which is the leaf next to manifold 204 as seen in Fig. 3. This leaf has a central boring 2|2 extending completely therethrough and a icounterbore 2M extending a substantial distance into the face of this leaf connects with central boring ZIZ. Ports H6 and H8 extend completely through leaf 2H3 so that they are at all times in communication with the atmosphere.

Rigidly aflixed to the rear face of leaf 2H] by means of screws 220 as seen in Fig. 8 is an upstanding arm 222. As shown in Fig. 3, to the upper end of arm 222 is pivotally connected link 224. Leaf 2H) is rotatably mounted upon hollow shaft 225 which is rigidly affixed to manifold 204. Line 228 connects this manifold with a constant source of vacuum, the duct 20'! within manifold 204 communicating with port 205 in hollow shaft 226. Therefore, vacuum is present in this hollow shaft at all times. It will be realized therefore that vacuum enters hollow shaft 226 at all times and through port 236 in this hollow shaft, vacuum at all times is present in counterbore 2I4 which is in contact with the face of the middle leaf 232 as seen in Fig. 8. Atmosphere at all times enters ports 2I8 and 2I8 which'likewise are in contact with the face of leaf 232. A plug 234 is in the end of hollow shaft 226 so that the vacuum may not escape therethrough. Within plu 234 is a threaded member 236 to the outer end of which is pivotally attached the upper end of link 208 which, as stated above, is intermediately connected with the air and vertical speed indicators and the altimeter.

Fig. 6 shows in detail the construction of the middle leaf 232. This leaf is also mounted upon hollow shaft 226 but cannot rotate thereupon because of the presence of screw 238. It will be seen that this leaf has a port 248 which extends completely therethrough and which is in perfect engagement with the counterbore 2I4 of leaf 2 II! when leaf 2I0 is in its central position. Fig; 8 shows that leaf in its central position. Two other ports 242 and 244 likewise extend completely through leaf 232 and are also in engagement with the ports H and 2IB respectively when leaf 2I6 is in its central position. If leaf 2I6 be centered, therefore, reduced air pressure will be present in port 240 and atmospheric pressure will be present'in ports 242 and 244. All three of these ports are in engagement with the face of leaf 246 as seen in Fig. 8.

The construction of leaf 248 is shown in detail in Fig. 7. It will be seen that rigidly affixed to the outer face of this leaf by means of the previously mentioned screws 206 is cross piece I96 to which reference has also been made. Two ports 24B and 256 extend from the bottom face of leaf 246 as seen in Fig. 8 a substantial distance within that leaf and then turn at right angles to communicate with the circular periphery of this leaf. A tubular piece 249 isinserted in this right angle extension of port 248 and a similar piece 25I is in like-arrangement with port 250.

Whenever bar I66 is in the horizontal position, ports 248 and 258 are in relation to the ports 240, 242 and 244 of leaf 232 as shown in Fig. 6. The ports 243 and 258 are shown in dotted outline in that figure, and it will be seen that port 248 slightly overlaps port 242 while port 258 slightly overlaps port 244. Therefore, whenever bar I96 is in the horizontal position as seen in Fig. 3, atmosphere will be admitted to both of the ports 248 or 250 and will be applied to connections 252 and 254 which are connected to the outer extensions 249 and 25! of ports 248 and 250. As seen in Fig. 3, connection 252 is connected to bellows designated generally as 255 and a bleed hole 253 is present in this connection. Connection 254 is connected to bellows designated generally as 258 and bleed hole 255 is present in that connection. Bar I96 is in the horizontal position only in case both throttles 38 and 84 have a like setting and therefore whenever these throttles are thus set, bellows 256-and- 258 will remain in their normal positions, i. e., filled with air at atmospheric pressure.

Referring to Fig. 3, in the event that throttle 38 be opened to a greater extent than throttle 84, link I94 will force the left end of bar I96 to a lower position than the right end of that bar will be forced by link I98. Leaf 246 to which bar I96 is connected will therefore rotate upon shaft 225 and port 248 'ofleaf 246' will communicate. with port 240 of leaf 232 and port 250 ofleaf 246 will communicate to a greater extent with port 244 of leaf 232. Vacuum will therefore be applied from port 248 to port 248 through connection 252 to bellows 255 while an increased amount of atmosphere will be applied through ports 244, 256 and connection 254 to bellows 258. Bellows 258 will therefore expand and bellows 256 will contract;

Referring to Fig. 3, the side 260 of bellows 256 is the side toward the front of the trainer and is rigidly affixed to any suitable stationary part of the trainer fuselage. The rear side 251 of this bellows is the movable side and has connected to its top by suitable pivotal means a link 261 which has its other endlikewise attached to the left end of rudder bar 252. This bellows is, of course, made airproof. It will be appreciated that as bellows 256 expands and contracts, side 251 will move back and forth and rudder bar 262 through the action of link 26I will be made to turnabout pivot 264. This movement will affect the position of rudder valve link 266 which controls the position of the rudder valve (not shown). As stated earlier in the description, a movement of link 266 will affect the rudder valve-which in turn will cause the trainer to turn about its vertical axis as is described and claimed in U. S. Patent 2,099,857.

Bellows 258 is similar in all respects to bellows 256 and is connected to rudder bar 262 by means of link 268. It should be noted, however, that a contraction of bellows 258 has the same effect upon the position of rudder bar 262 and rudder valve link 266 as does an expansion'of bellows 256.

Rudder pedals 210 and 212 are rotatably mounted upon the shaft 214' which is rigidly held by bracket 216. If rudder'pedal 216 be pushed forward, link 218 which is attached to the lower extension of this rudder pedal at a point below shaft 214 will move to the rear, the left end of rudder bar 262 will move in the same direction and link 266 will move to the rear, thereby affecting the rudder valve and causing the trainer-to turn to the left; but if rudder pedal 212 be pushed forward, link 286 will move in the opposite direction and thetrainer will turn to the right. It is also to be noted that a contraction of bellows 258 affects rudder valve link 266 in the same manner as though pressure were applied to rudder pedal 216. The same is true of bellows 256 and pedal 212.

Therefore, whenever throttle 38 be opened to a greater extent than throttle 84, vacuum is admitted through connection 252 to bellows 256 and at the same time an increased amount of atmosphere is admitted through'connection 254 to bellows 258. The former bellows will contract and the latter will expand. The right end of rudder bar 262 will move toward the rear of the trainer just as though pressure were applied to rudder pedal 212. move toward the head of the trainer and the trainer will turn to the right. Bearing in mind the fact that throttle 84 which is the assumed right motor throttle is not opened as far as the assumed left motor throttle 38, it will be realized that the foregoing means cause the trainer to turn in-the direction of the slower motor in exact simulation of the turning in the direction of the slower motor of a dual motored plane in actual flight. Such means are described and claimed in Rudder valve link 266 will 17 the aforementioned companion application Serial No. 448,906.

This turning of a dual motored plane in actual flight caused by a difference in motor speeds is diminished as such a plane is banked until when a certain angle of bank is'reached the turning effect completely disappears. The following means are incorporated in the instant invention to simulate such a disappearance of rudder loading when a dual motored plane is banked.

Referring to Figs. 3, 5, and 8, it has been mentioned that an extension 222 is aflixed to leaf 2") by means of screws 226. As seen in Fig. 3, to the upper end of this extension is pivotally connected link 224, the other end of which is pivotally connected to the upper end of arm 282. Arm 282 pivots about the point at which the shaft 286 is rigidly afiixed thereto. The other end of this shaft is rigidly affixed to arm 288 which also pivots about the point where shaft 286 connects thereto.

To the lower end of lever 288 is pivotally connected the link 292 and the other end of link 292 is pivotally connected to the central support I of the trainer fuselage which is located below the universal joint I2. Arm 288 is pivotally mounted upon any suitable part of the interior of the trainer fuselage 16. It will be appreciated therefore that whenever the trainer is banked laterally in either direction, link 292 will cause arm 288 to pivot in one direction or the other, the extent of such rotation depending upon the degree of the bank. This movement of lever 288 will cause shaft 286 to rotate in one direction or the other and the rotation of this shaft will cause the upper end of arm 282 to move toward one side of the trainer fuselage or the other and therefore link 224 will likewise reciprocate, moving extension .222 and causing leaf 2I6 to rotate upon hollow shaft 226. The rotation of leaf 2I6 will move vacuum-filled counterbore 2I4 out of perfect engagement with port 246 of leaf 232,'and atmospheric ports 2I6 and 2I8 will be moved out of exact engagement with ports 242 and 244 respectively of leaf 232. Therefore, less vacuum will be applied to port 246 and less atmosphere will be applied to ports 242 and 244. Consequently, less vacuum and less atmosphere will be applied to the ports 248 and 256 if the throttles of the trainer be in such a position that the ports in leaf 246 are in communication with the ports in leaf 232.

In illustration, let us assume that throttle 84 be opened to a greater extent than throttle 36, that is, it be moved farther to the left in Fig. 3 than throttle 36. Link I98 will be forced downwardly to a greater extent than link I94 and, therefore, port 256 of leaf 246 will communicate with port 246 of leaf 232 while port 248 of the former leaf will be in greater communication with port 242 of the latter leaf. Vacuum will be applied through connection 254 to bellows 258 while a greater amount of atmosphere will be applied through connection 252 to bellows 256. The former bellows will contract and the latter will expand and rudder valve link 266 will be moved so that the trainer will be made to turn to the left. Now assuming that the trainer be banked in either direction, by means of link 292, arm 288, link 286, arm 282, link 224 and arm 222, leaf 2I6 will be made to rotate upon hollow shaft 226 and vacuum-filled counterbore 2 [4 will become out of perfect engagement with port 246, less vacuum will be applied to port 240 of leaf 232 and, therefore, less vacuum will be applied to port 256 of leaf 246. Likewise, a reduction in the amount of were actually applying vacuum applied to bellows 258 will result and air entering bleed hole 255 will cause that bellows to expand. At the same time, less atmosphere will be applied through port N6 of leaf 2I6 to port 242 in leaf 232 and, therefore, a reduction in the amount of atmosphere entering port 248 of leaf 246 will result. A similar reduction will affect connection 252 and less atmosphere will enter bellows 256 which bellows therefore will be made to contract. The expansion of bellows 258 and the contraction of bellows 256 will offset the torque applied to rudder bar 262 as a result of the unequal throttle settings. The turning of the trainer .to the left, caused by an opening of throttle 84 to "a greater extent than throttle 36 will therefore be diminished by the banking of the trainer in either direction. If the trainer were turning in the opposite direction as a result of throttle 36 being opened farther than throttle 84, a banking of the trainer in either direction would likewise diminish the turning so caused.

In dual motored planes, there is often times provided means in addition to the pilots applying his foot to one of the rudder pedals which may be used to prevent the turning of the plane in the direction of the slower motor.

In a real plane these means are of two types, one means providing its compensation through positioning the rudder pedals and the other through positioning a tab on the rudder of the plane. Inasmuch as such compensating means in the trainer must be related to the rudder valve, the following means which have been incorporated in my invention in order that the student in the trainer may have at his disposal means for accomplishing the sameresult may be considered to be of either type.

Referring to Fig. 3, it will be seen that a winch comprising a worm 286 and a worm wheel 2% are provided. An arm 366 is rigidly affixed to the wheel 298 so that-whenever this wheel be rotated through a turning of worm 296 the link 362 which is pivotally attached to the upper end of arm 366 is moved one way or the other depending upon the direction of rotation of the wheel 298. The other end of link 362 will move arm 364 which in turn will cause the chain sprocket 366 to turn. The rotation of this sprocket will move chain 368 in one direction or the other and the tension upon the spring 3I6 will be increased or decreased and at the same time the tension upon spring 3I2 will be decreased or increased. Inasmuch as spring 3! is connected to link 8I4,

,the other end of which is connected to the upper end of rudder pedal 2'56 while the other end of spring 3I2 is connected to link 3H5 which has its other end connected to the upper part of rudder pedal 212, it will be realized that an increase in the tension upon spring 3H) and the simultaneous decrease in the tension upon spring SIZ will cause the rudder pedals to move in the same manner as though the student in the trainer were applying his left foot to left rudder pedal 216, while if the worm 296 be turned in such a direction that the tension upon spring 312 be increased and that upo'nspring 3 I 6 be decreased the rudder pedals will respond as though the student in the trainer his right foot to rudder pedal 212. A suitable scale 3l8 and an index mark 326 on the wheel 298 are provided so that the student in the trainer, by referring to the tachometers I64 and I12 and thus learning the difference in the assumed motor speeds, may position the wheel 298 correctly to overcome the turning of the trainer caused by the unequal throttle settings.

In the event that one of the bellows 256 or 258 be substantially contracted through the application of vacuum by means of connections 252 or 254, the natural response of the student in the trainer would be to apply his foot to the rudder pedal on the side of the contracted bellows. In order to overcome the atmospheric iorce being exerted on the outside of the contracted bellows, the student would be required to exert an inordinately large amount of force on the pedal. In order to overcome this difiiculty the links 261 and 258 are in reality positive type spring compensator link rods. The detailed construction of these linksis shownin Fig. 3A. The left end .322 of this rod is connected to the upper part of the bellows 256 or 258 and the project through the slot 328 which is in either side of the housing 326. A compression spring 332 is within housing 326, one end of this spring bearing against the interior right end of housing 326 as seen in Fig. 3A and the other end bearing against the horizontal stop 330. Spring 332 is of such a compression that Whenever either of the bellows 256 or 258 is collapsed by an application of vacuum thereto, the stop 330 does not move substantially in slots 328 and therefore the movement of rudder bar 262 is not substantially affected, but in the event that either bellows 256 or 258 be contracted because of the reduced air pressure therewithin, if the student in the trainer applies his foot to the rudder pedal 210 or 212 on the side of the contracted bellows, the movement of rudder bar 262 will cause a contraction of spring 332 and consequently, rudder bar 262 will be able to move even though the bellows in question continue to be contracted.

Therefore, my invention provides means in addition to applying his feet to the rudder pedals whereby the student in the trainer may overcome the turning of the trainer caused by a dif ference in the assumed motor speeds.

It may be concluded that my invention provides means whereby the response of an airplane and many of the instruments thereof to many conditions of actual flight may be simulated in a grounded aviation trainer. Changes may be made in the details of construction and arrangement of parts without departing from the spirit and scope of this invention. All such modifications are intended to be included within the following claims.

I claim:

1. In a grounded aviation trainer, means for simulating the functioning of a manifold pressure gauge in a real plane, said means comprising the combination of a simulated manifold pressure gauge, means in said trainer for actuating said simulated gauge to indicate assumed manifold pressures, a simulated throttle in said trainer, and means operated by said simulated throttle for causing said actuating means to cause said simulated gauge to register in accordance with the setting of said simulated throttle.

2. In a grounded aviation trainer comprising a fuselage capable of changing its attitude in simulation of the climbing and diving of a plane in actual .fiightmeans for simulating thefunctioning of a manifold pressure gauge in a real plane, said means comprising the combination of a simulated manifold pressure gauge, means iii-said trainer for actuating said simulated gauge-toindicate assumed manifold pressures, and means responsive to the attitude of said fuselage for trainer for actuating said simulated gaugeto;in-

dicate assumed manifold pressures, a simulated throttlein said trainer, andmeans operated by the attitude of said fuselage as well as by said simulated throttle for causing said actuating means to cause said simulatedgauge to-register in accordancewith the attitude-of said fuselageand the position of said simulated throttle.

4. Ina grounded aviation trainer,- means for simulating the functioning of amanifold'pressure gauge in a real plane, said meanscomprisingthe combination of a simulated ,;ma nifold pressure gauge and means in said trainer f or actuating 7 said simulated gauge to indicate assum d :manifold pressures; an equalizer tank within said trainer; -means for varying the pressure within said equalizer tank according to the assumed altitude of said trainer; a throttlesimulat d member in said trainer; and means foreausingsaid actuating means to cause said simulated gauge to register in accordance with the press re W thi sai equ izer tank; and means. independent of said equalizer tank for causing said simulated au t register in r p n e t th .1posit on f :said throttle simulating member.

L5.'In a'grounded aviation trainer comprisinga fuselage capable of changing-its attitude-.insimulation of the climbing and diving of;a plane in actual :fiight means for simulating the functioning of ,a manifold pressure gauge inareal plane, said means comprising the combination of a simulated manifold-pressure gaugeand-means in said trainer for actuating said simulated gauge to insaid actuating means to cause said simulated gauge to register in accordance .wijth the pressure within said equalizer tank; andmeans-independent of said equalizer tank for causing said simulated gauge to register in'responseto .the attitude of said fuselage.

6. Ina grounded aviation trainer comprising a fuselage capable of changing itsattitude insimulation of the climbing and diving of a plane in actual flight means for simulating the functioning of a manifold. pressure gau'gein a real :plane, said means comprising the combination of asimulated manifold pressure gauge :and means in said trainer for actuating said gauge .toindicate assumed manifold pressurespan equalizer tank in said trainer; means for varying :theipressure within said tank in accordance with the .assumed altitude of .said trainer; 2. throttle simulating me ber i s raine means for causin ai a uat n 11621 1511 au e said imul d gau t register-in accordance-with the pressure within said tank; and means independent of said equalizer tank for causing said simulated gauge .to register in response to the attitude of said fuselage and position of said throttle simulating member.

'7. In a grounded aviation trainer, means for simulating the functioning of a manifold pressure gauge and a tachometer in a real plane, said means comprising the combination of a simulated manifold pressure gauge means in said trainer for actuating said simulated gauge to indicate assumed manifold pressures, a simulated tachometer and means in said trainer for actuating said simulated tachometer to indicate assumed motor speeds, a simulated throttle in said trainer, and

means operated by said simulated throttle for causing said first-mentioned actuating means to cause said simulated manifold pressure gauge and the other of said actuating means to cause said simulated tachometer to register in accordance with the setting of said simulated throttle.

8. In a grounded aviation trainer comprising a fuselage capable of changing its attitude in simulation of the climbing and diving of a plane in actual flight means for simulatin the functioning of a manifold pressure gauge and a tachometer in a real plane, said means comprising the combination of a simulated manifold pressure gauge, means in said trainer for actuating said simulated gauge to indicate assumed manifold pressures, a simulated tachometer in said trainer and means in said trainer for actuating said simulated tachometer to indicate assumed motor speeds, and means responsive to the attitude of said fuselage for causing said first-mentioned actuating means to cause said simulated manifold pressure gauge and the other of said actuating means to cause said simulated tachometer to register in accordance with the attitude of said fuselage.

9. In a grounded aviation trainer comprising a fuselage capable of changing its attitude in simulation of the climbing and diving of a plane in actual flight means for simulating the functioning of a manifold pressure gauge and a tachometer in a real plane, said means comprising the combination of a simulated manifold pressure gauge, means in said trainer for actuating said simulated gauge to indicate assumed manifold pressures, a simulated tachometer and means in said trainer for actuating said simulated tachometer to indicate assumed motor speeds, a simulated throttle in said trainer, and means responsive to the attitude of said fuselage as well as to the position of said simulated throttle for causing said first-mentioned actuating means to cause said simulated gauge and the other of said actuating means to cause said simulated tachometer to register in accordance with the attitude of said fuselage as well as the setting of said simulated throttle.

10. In a grounded aviation trainer, means for simulating the functioning of a manifold pressure gauge and a tachometer in a real plane, said means comprising the combination of a simulated manifold pressure gauge, means in said trainer for actuating said gauge to indicate assumed manifold pressures, a simulated tachometer and means in said trainer for actuating said simulated tachometer to indicate assumed motor speeds, a throttle simulating member and an equalizer tank within said trainer, means for varying the pressure within said tank according to the assumed altitude of said trainer, and means for causing said first-mentioned actuating means to cause said simulated manifold pressure gauge to register in accordance with the position of said throttle simulating member and the pressure within said equalizer tank and the other of said actuating means to cause said simulated tachometer to register in accordancewith the position of said throttle simulating member.

11. In a grounded aviation trainer comprising a fuselage capable of' changing its attitude in simulation of the climbing and diving of a plane in actual flight, means for simulating the functioning of a manifold pressure gauge and a tachometer in a real plane, said means comprising the combination of a simulated manifold pressure gauge, means in said trainer for actuating said simulated gauge to indicate assumed manifold pressures, a simulated tachometer and means in said trainer for actuating said simulated tachometer to indicate assumed motor speeds, an equalizer tank in said trainer, means for varying the pressure within said tank according to the assumed altitude of said trainer, and means for causing said first-mentioned actuating means to cause said simulated manifold pressure gauge to register in accordance with the attitude of said fuselage as Well as the pressure within said equalizer tank and the other of said actuating means to cause said simulated tachometer to register in accordance with the attitude of said fuselage.

12. In a grounded aviation trainer comprising a fuselage capable of changing its attitude in simulation of the climbing and diving of a plane in actual flight, means for simulating the functioning of a manifold pressure gauge and a tachometer in a real plane, said means comprising the combination of a simulated manifold pressure gauge, means in said trainer for actuating,

said simulated gauge to indicate assumed manifold pressures, a simulated tachometer in said trainer and means in said trainer for actuating said simulated tachometer to indicate assumed motor speeds, a simulated throttle and an equalizer tank within said trainer, means for arying the pressure within said tank according to the assumed altitude of said trainer, and means for causing said first-mentioned actuating means to cause said simulated manifold pressure gauge to register in accordance with the attitude of said fuselage, the pressure within said equalizer tank and the position of said simulated throttle and the other of said actuating means to cause said simulated tachometer to register in accordance with the attitude of said fuselage and the position of said simulated throttle.

13. In a grounded aviation trainer, means for simulating the functioning of the manifold pressure gauges in a plural engine aircraft, said means comprising the combination of a plurality of simulated manifold pressure gauges, a plurality of independent means in said trainer for actuating each of said simulated gauges to indicate assumed manifold pressures, a plurality of simulated throttles in said trainer, one of said simulated throttles being associated with each of said actuating means, and means for causing each of said actuating means to cause its associated simulated gauge to register in accordance with the set ting of its associated simulated throttle.

.14. In a grounded aviation trainer comprising a fuselage capable of changing its attitude in simulation of the climbing and diving of a plane in actual flight, means for simulating the functioning of the manifold pressure gauges in a plural engine aircraft comprising the combination of a plurality of simulated manifold pressure simulated manifold pressure gauges, means in said trainer for actuating each of said simulated gauges to indicate assumed manifold pressures, an equalizer tank within said trainer, means for varying the pressure Within said equalizer tank according to the assumed altitude of said trainer, and means responsive to the pressure within said equalizer tank for causing said actuating means to cause each of said simulated gauges to register in accordance with the pressure within said equalizer tank,

16. In a grounded aviation trainer comprising a fuselage capable of changing its attitude in simulation of the climbing and diving of a plane in actual flight, means for simulating the functioning of the manifold pressure gauges in a plural engine aircraft comprising the combination of a plurality of simulated manifold pressure gauges, a plurality of independent means in said trainer for actuating each of said simulated gauges to indicate assumed manifold pressures, a plurality of simulated throttles in said trainer, one of said simulated throttles being associated with each of said actuating means, and means operable by each of said simulated throttles for causing its associated actuating means to cause its associated simulated gauge to register in accordance With the setting of its associated simulated throttle, and means for causing each of said simulated gauges to register in accordance with the attitude of said fuselage.

17. In a grounded aviation trainer, means for simulating the functioning of the manifold pressure gauges in a plural engine plane, said means comprising the combination of a plurality of simulated manifold pressure gauges, a plurality of independent means in said trainer for actuating each of said simulated gauges to indicate assumed manifold pressures, a plurality of simulated throttles in said trainer, one of said simulated throttles being connected with each of said actuating means, an equalizer tank 'in said trainer, means for varying the pressure Within said tank according to the assumed altitude of said trainer, and means operable by each of said simulated throttles for causing its associated actuating means to cause its associated simulated gauge to register in accordance with the setting of its associated simulated throttle, and means for causing each of said gauges to register in accordance with the pressure Within said equalizer tank,

18. In a grounded aviation trainer comprising a fuselage capable of changing its attitude in simulation of the climbing and diving of a plane in actual flight, means for simulating the functioning of the manifold pressure gauges in a plural engine plane comprising the combination of a plurality of simulated manifold pressure gauges, a plurality of independent means in said trainer for actuating each of said simulated gauges to indicate assumed manifold pressures, a, plurality of simulated throttles in said trainer, one of said simulated throttles being associated with each of said actuating means, an equalizer tank'in said trainer, means for varying the pressure Within said tank according to the assumed altitude of said trainer, and means for causing each of said actuating means to cause its associated simulated gauge to register in accordance with the setting of its associated simulated throttle, the attitude of said fuselage and the pressure within said equalizer tank.

19. In a grounded aviation trainer the combination of, a plurality of simulated manifold pressure gauges, independent means in said trainer for actuating each of said simulated gauges to indicate assumed manifold pressures, a simulated air speed indicator in said trainer, means responsive to certain controls in said trainer for actuating said simulated indicator to indicate assumed air speeds, and a plurality of simulated throttles in said trainer, one of said simulated throttles being associated with each of said simulated gauge actuating means, and all of said simulated throttles being associated with said simulated air speed indicator actuating means, means for causing each of said simulated gauge actuating means to cause its associated simulated gauge to register in accordance with the position of its associated simulated throttle, and means for causing said simulated air speed indicator to register in accordance with the combined positions of said simulated throttles.

20. In a grounded aviation trainer, the combination of a plurality of simulated manifold pressure gauges, independent means'insaid trainer for actuating each of said simulated gauges to indicate assumed'manifold pressures, an equalizer tank within said trainer, means for varying the pressure within said tank, a simulated instrument connected to said equalizer tank and responsive .to the pressure therewithin, a plurality of simulated throttles in said trainer, one of said simulated throttles being associated with each of said simulated gauge actuating means, and all of said simulated throttles being associated *with said means for varying the pressure within said tank, means'for causing each'of said gauge actuating means to cause its associated simulated manifold pressure gaugeto register in accordance with the position of "its associated simulated throttle, and means for varying the pressure within said equalizer tank in accordance with the combined positions of said simulated throttles.

21. In a grounded aviation trainer the combination of a'plurality of simulated tachometers, a plurality of independent means in said trainer for actuating each of said simulated tachometers to indicate assumed motor speeds, a plurality of simulated throttles in said trainer, one of said simulated throttles being associated with each of said actuating means, a simulated air speed indicator in said trainer, means in said trainer for causing said indicator to indicate assumed air speeds, all of said simulated throttles being associated with said last-mentioned actuating means, and means for causing each of said simulated tachometer actuating means to cause its associated simulated tachometer to register in accordance With the position of its associated simulated throttle, and means for causing said simulated air speed indicator to register in accordance with :the combined positions of said simulated throttles.

22. In a grounded aviation trainer the combination ofa plurality of simulated tachometers, a plurality of independent means in said trainer for actuating each-of said simulated tachometers to indicate assumed motor speeds, a plurality of simulated throttles in said trainer, one of said simulated throttles being associated with each of said actuating means, an equalizer tank within said trainer, means for varying the pressure within said tank, all of said simulated throttles being associated with said last-mentioned means, a simulated instrument connected to said equalizer tank and responsive to the pressure therewithin, and means for causing each of said simulated tachometer actuating means to cause its associated simulated tachometer to register in accordance with the position of its associated simulated throttle, and means for varying the pressure within said equalizer tank in accordance with the combined positions of said simulated throttles.

23. In a grounded aviation trainer, means for simulating the functioning of a manifold pressure gauge and an air speed indicator in a real plane, said means comprising the combination of a simulated manifold pressure gauge and a simulated air speed indicator, means in said trainer for actuating said simulated gauge to indicate assumed manifold pressures and means in said trainer for actuating said simulated air speed indicator to indicate assumed air speeds, a simulated throttle in said trainer, and means operated by said simulated throttle for causing both of said actuating means to cause said simulated manifold pressure gauge and said simulated air speed indicator to register in accordance with the setting of said simulated throttle.

24. In a grounded aviation trainer the combination of a fuselage rotatably mounted upon a stationary base, means for rotating said fuselage about its vertical axis, a plurality of simulated tachometers in said fuselage, a plurality of independent means in said trainer for actuating each of said simulated tachometers to indicate assumed motor speeds, a plurality of simulated throttles in said trainer, one of said simulated throttles being associated with each of said actuating means, means for causing said rotating means to rotate said fuselage according to the relative positions of said throttles, and means for causing each of said simulated tachometer actuating means to cause its associated simulated tachometer to register in accordance with the position of its associated simulated throttle. e

25. In a grounded aviation trainer the combination of a fuselage rotatably mounted upon a universal joint, means for banking said fuselage in simulation of the banking of an airplane in actual flight and means for rotating said fuselage about its vertical axis, a plurality of simulated throttles within said fuselage, means for causing said rotating means to rotate said fuselage according to the relative positions of said simulated throttles, and additional means responsive to the lateral position of said fuselage for diminishing the rotation of said fuselage caused by said relative simulated throttle positions whenever said fuselage is banked.

26. In a, grounded aviation trainer the combination of a fuselage rotatably mounted upon a universal joint, means for banking said fuselage laterally in simulation of the banking of an airplane in actual flight, means for rotating said fuselage about its vertical axis, a plurality of simulated throttles within said fuselage, and a control element for controlling the rotation of said fuselage responsive to the combined settings of said simulated throttles as well as to the lateral position of said fuselage, said control ele- 26 ment causing said rotating means to rotate said fuselage according to the relative positions of said simulated throttles as well as the lateral position of said fuselage.

2'7. In a grounded aviation trainer the combination of a fuselage rotatably mounted upon a universal joint, means for rotating said fuselage about its vertical axis according to theposition of a control element, a plurality of simulated 10- throttles in said fuselage, the position of said control element being responsive to the combined positions of said simulated throttles, and manually operable means for offsetting the positioning of said control element caused by th combined positions of said simulated throttles.

28. In a grounded aviation trainer the combination of a fuselage rotatably mounted upon a universal joint, means for rotating said fuselage about its vertical axis according to the position -of a control element, a plurality of simulated throttles and a pair of simulated rudder pedals in said fuselage, the position of said control element being responsive to the combined positions of said simulated throttles as well as the position of said simulated rudder pedals, and manually operable means in addition to said simulated throttles and said simulated rudder pedals for pcsitioning said control element.

29. In an airplane trainer including a turnable cockpit, and control means for turning the cock pit, the combination therewith of a pair of simulated manifold pressure gauges to indicate assumed manifold pressures, a plurality of independent means in said trainer for actuating each of said simulated gauges, a plurality of simulated throttle control levers in said trainer, one of said simulated throttles being associated with each of said actuating means, means for causing said control means to rotate said, trainer according to the relative positions of said throttles, and means for causing each of said simulated gauge actuating means to actuate its associated gauge to register in accordance with the position of its associated throttle.

30. In a grounded aviation trainer, means for simulating the functioning of a manifold pressure gauge in a real airplane, said means comprising the combination of a simulated manifold pressure gauge and means for actuating said simulated gauge to indicate assumed manifold pressures; an equalizer tank within said trainer; means for varying the pressure within said tank according to the assumed altitude of the trainer; means responsive to the pressure within said tank for causing said actuating means to cause said simulated gauge to register in accordance with the assumed altitude of said trainer; and additional means operatively connected to said actuating means for affecting the indication of said simulated gauge.

31. In a grounded aviation trainer, means for simulating the functioning of a manifold pressure gauge in a real plane, said. means comprising, in combination, a simulated manifold pressure gauge, means forming a part of said trainer arranged to be operable in response to the movements of a throttle control simulating member in said trainer and means forming a part of said trainer operable in response to changes in the assumed altitude of said trainer, means interconnecting the means responsive to the throttle control simulatin member and said gauge for changing the reading of said gauge in response to the operations of said means responsive to the throttle control simulating member, and means interconnecting saidaltitude-responsive means. and said gauge for-changing the'reading ofisaid:

cateassumed altitudes, a plurality ofv means in said trainer each responsive toda: difierent tone 7 of aplurality of throttlecontrolisimulating mema hers, and meansiinterconnecting theplurality of means responsive. tov thethrottlecontrol simulating. members-V andv said instrument actuating,

means for causing said-actuating means to cause said. indicator, to register. inaccordance with the combined: effect of. said means responsive toithe throttle control simulating members.

33'. In. a groundedaviation trainer, the combination of .antinstrument in" said trainer simutlatingthe. vertical speed-indicator of airealplane; meansiinisaid trainer ,for actuating said instru-- mentto indicate assumed-vertical.speeds, a phi.-

28: rality'ofmeans in said trainer eachresponsive to a difierent one of; a-plurality of throttle control simulating; members andmeans interconnecting the plurality of means responsive to the throttle 5-; control simulatingfmembers and said instrument actuating means for: causing said actuating means to cause-said indicator to register in accordance-with the-combined efiect of said means responsive to the throttle control simulating members;

KARL A. KAIL.

REFERENCES CITED Theuiollowingr references are of record in the filiof" this patent:

UNITED STATES PATENTS Number Name Date 1,825,462 Link "Sept. 29, 1931 2,099;857- Link Nov. 23, 1937 2;2 12,931= 'Colvin- Aug 27, 1940 2,-301 685 DeFlorez- Nov. 10, 1942 2; 3t66,-603- Dehmel: Jan, 2, 1945 

